282 BULLETIN OF THE UNITED STATES FISH COMMISSION. 
of disease in a fish are a generally drooping appearance, the fins being 
closed or depressed, its movements being slow and languid — altogether 
different from its usually lively and graceful motions. The presence of 
the microscopic parasites which often infest the gold-fish in aquaria is 
made known by an inclination in the fish to keep the fins close to the 
body, at times flapping them rapidly and darting about as if intensely 
irritated. There will be generally in this case a raw or bloody appear- 
ance about the bases of the fins, and at the edges of the scales, and 
the fins may become closed, the rays being drawn together and termi- 
nating in a sharp point. Fish may be freed from these pests by taking 
them up carefully in a soft net and dipping them in strong salt water 
for a few seconds once or twice a day, or brushing them with a soft 
brush or sponge dipped in salt water. Carbolic acid diluted is some- 
times used and other remedies are sometimes recommended, but the 
salt bath is quite as efficacious as any of them, and less dangerous to 
the fish. Diseased fish may often be cured by putting them in a tub 
of water with some aquatic plant out in the open air when the weather 
will permit, or in winter in a light place if with plants, and in semi- 
darkness if without. Sudden changes of temperature in changing the 
water are sure to produce inflammation of the gills (lungs) and other dis- 
eases apparently analogous to those of mankind produced by similar 
causes. But little is known of the diseases of fish, and there is plenty 
of room for experiment in treatment. Very strangely the minute para- 
sites so common to the gold-fish do not appear to infest other kinds. 
There is a disease quite common among gold-fish and carp, in which 
there is a quantity of water between the skin and body of the fish, and 
the scales stand out from the body almost at right angles. They rarely 
recover and no cure is known. Where fish have proper conditions and 
are not crowded these diseases are very rare. Fungous growths occur 
where the scales or mucous covering are scratched or rubbed off. The 
germs of this class of parasitic plants are generally present in water, 
and are sure to develop upon any animal, and sometimes vegetable 
matter which may be present in a state of inflammation or of decompo- 
sition. Sometimes the fins of fish will be destroyed by these growths, 
but will soon grow again when the fungus is removed. The salt-water 
bath is the simplest and best means of removing or destroying it. 
RECAPITULATION. 
A brief recapitulation recalls four points demanding especial consid- 
eration as absolutely essential to success in the management of the 
aquarium. They are, first, absolute purity in the vessel used ; second, 
an abundance of light; third, to avoid overstoching with fish ; and, fourth, 
great care in introducing food into the aquarium . A careful observance 
of these principles will lead to success. To ignore them is to invite 
failure. 
